Non-wetting surface design with magnetic and visible-light-active properties and its application to pollutant treatment

How to deal with organic pollutants of different densities and water-soluble pollutants is a challenge. In this paper, the slurry containing photocatalyst Ag₃PO₄, alkylated Fe₃O₄ and adhesive layer polydimethylsiloxane can be loaded to various substrates (including fabric, sponge, cotton) with a simple adsorption method. The non-wetability to water and the oleophilicity to organic solvent were realized by reducing the surface tension of solid through alkyl chain. It can not only remove pollutants floating on the water surface, but also adsorb pollutants whose density is greater than water and then realize the recovery with the response of the external magnetic field. It is important that the Ag₃PO₄ photocatalyst component in the material can absorb light energy to degrade water-soluble pollutants and further improve water quality. The stability tests (involving ultrasonic treatment, boiling water treatment and compression experiments) show that the prepared precursor slurry shows an excellent bonding stability with various substrates. Furthermore, graphene oxide has the best photodegradation behavior when 4 mg are added. Finally, photodegradation mechanism, the conduction (2.665 eV) and valence band (0.195 eV) information of the catalyst were analyzed.     

Photocatalytic degradation of basic blue 9 by CoS nanoparticles supported on AlMCM-41 material as a catalyst

In this investigation photocatalytic degradation of basic blue 9 or methylene blue (MB) as color pollutants was studied. Cobalt sulfide was supported on AlMCM-41 material using ion-exchange method. The results show that CoS/AlMCM-41 is an active photocatalyst. The catalyst is characterized by X-ray diffraction (XRD) UV–vis diffused reflectance spectra (UV–vis DRS) and scanning electron microscopy (SEM) techniques. The maximum effect of photodegradation was observed at 7 wt% CoS/AlMCM-41. Pseudo-first order reaction with k = 0.032 was observed for the photocatalytic degradation reaction. The effect of some parameters such as pH, amount of photocatalyst and initial concentration of dye were also examined. The effect of dosage of photocatalyst was studied in the range 0.04–1.2 g/L. It was seen that 0.8 g/L of photocatalyst is an optimum value for the dosage of photocatalyst. In the best conditions, the degradation efficiency was obtained 0.32 ppm for MB dye.     

Photocatalytic degradation of reactive black-5 dye using TiO<Subscript>2</Subscript> impregnated ZSM-5

In the present study, photocatalytic degradation of reactive black-5 (RB-5) dye was investigated using supported TiO₂ photocatalyst based adsorbent as a semiconductor photocatalyst in a batch reactor. The synthesized photocatalyst composition was developed using TiO₂ as photoactive component and zeolite (ZSM-5) as the adsorbents. Attempts were also made to optimize the composition of the supported catalyst and to study the reliability of prepared catalyst. The optimum formulation of supported catalyst was found to be (TiO₂: ZSM-5 = 0·15:1) which gave the highest efficiency with 98% degradation of 50 mg/L RB-5 solution in 90 min. Effect of different parameters such as initial concentration of dye solution, catalyst amount on the rate of photodegradation was also studied. The reduction in the chemical oxygen demand (COD, 88%) proves the mineralization of the RB-5 dye along with the colour removal. The supported TiO₂ was found to be stable for repeated use.     

Efficient SiO2/WO3–TiO2@rGO nanocomposite photocatalyst for visible-light degradation of colored pollutant in water

The photoactive SiO₂/WO₃–TiO₂@rGO nanocomposite was fabricated through sol–gel, microwave, and hydrothermal approaches for the photodegradation of methylene blue (MB) as an organic-colored pollutant. The nanocomposite photocatalysts were formulated by adjustment of the ingredients content to achieve efficient synergic effects on photocatalyst performance. The results exhibited that optimum amount of SiO₂ and rise in WO₃/TiO₂ ratio as well as incorporation of reduced graphene oxide in structure can be led to further efficiency of degradation under visible light. The effect of sunlight irradiation, pH of MB solution, MB concentration, and lamp distance on photodegradation reaction were also investigated. The best performance about 99.9% MB degradation was obtained based on using 0.3 g/L of optimum photocatalyst to remove the 5 ppm MB solution with pH of 5.41 during 3 h irradiation by visible-light source with 30 cm distance from MB solution. As well, results showed that photocatalyst performance under visible light is better than sunlight irradiation. The most favorable photocatalyst indicated surface area of 60.9 m²/g. Furthermore, the reusability test indicated a proper activity after three cycles under the same conditions. So, the introduced efficient visible photoactive SiO₂/WO₃–TiO₂@rGO nanocomposite can be considered as an appropriate potential to remove organic pollutants in colored effluents.

     

Amorphous TiOBCN—A new solar photocatalyst

Amorphous photocatalyst TiOBCN was prepared for the first time. The TiOBCN showed obvious absorption in the visible light region up to 520 nm and 783 nm. The degradation rate of AO7 in TiOBCN solution increased quickly from 0% to 99.46% in 150 min after undergoing solar simulating irradiation. For TiO₂ the degradation rate of AO7 is just 57.2%.The experimental results also revealed that the degradation rate of AO7 first increases, and then decreases to a range concentration falling within 5 to 35 mg/L. The optimum catalyst loading for the degradation of AO7 is 400 mg/L.     

A novel AgMoOS bimetallic oxysulfide catalyst for highly efficiency catalytic reduction of organic dyes and Chromium (VI)

To detoxify chemical pollutants discharge from industries, the researchers pursue always to get new, cost-effective, environmentally friendly and efficient technologies. Herein, novel silver molybdenum oxysulfide (AgMoOS) catalyst which is monoclinic structure with spherical shape nanoparticle and uniform distribution of its elemental composition was successfully synthesized by a facile method. The catalytic performance of AgMoOS was employed for the reduction of methylene blue (MB), methyl orange (MO), 4-Nitrophenol (4-NP), Rhodamine B (RhB) and Chromium (VI) in presence of NaBH₄ under dark condition and a fastest reduction activity was obtained with 2-AgMoOS. A 10 mg of 2-AgMoOS completely reduced 100 mL of 20 ppm of MB, MO, 4-NP, RhB and Cr⁶⁺ within 6, 6, 15, 24 and 24 min, respectively and the reduction kinetic data indicated that the catalytic activity of all AgMoOS catalysts toward these chemical pollutants followed the order: MB > MO > 4-NP > RhB > Cr⁶⁺ ions. The re-usability data toward the reduction of MB, cyclic voltammogram, XPS and XRD spectrum of 2-AgMoOS after the reaction were confirmed a good stability and durability of AgMoOS catalyst. Hence, AgMoOS is an efficient catalyst and provides a practical application for toxic organic dyes degradation and toxic inorganic pollutants containing waste water treatment and other environmental issues.     

Enhancing solar photocatalytic activity of Bi5O7I photocatalyst with activated carbon heterojunction

Passive solar photocatalysis is one of the most efficient ways for the treatment of dye industry wastewater. Some dyes such as methyl orange are recalcitrant to photolysis; therefore, photocatalysts are used to expedite their degradation. Photocatalysts are semiconductors, and their activity can be improved by creating heterojunctions. In the current work, an active photocatalyst, Bi₅O₇I_, was modified with activated carbon (AC), obtained by controlled carbonization of pistachio shells, to give xAC-Bi₅O₇I photocatalysts. AC loading improved the surface area of the catalyst and decreased its bandgap to 1.8 eV, making it suitable for use as a visible light photocatalyst. Activated carbon enhances adsorption, while Bi₅O₇I scavenges adsorbed molecules increasing the efficiency. 5AC-Bi₅O₇I catalyst containing 5% activated carbon displayed the optimum photocatalytic activity, which was 3.4-fold higher than that of pristine Bi₅O₇I. 5AC-Bi₅O₇I achieved 99.9 % reduction in the concentration of methyl orange in 80 min under sunlight irradiation. 5% AC-Bi₅O₇I is more efficient than commercial Degussa P25 photocatalyst as well. The methyl orange degradation efficiency of the catalysts studied was: 5AC-Bi₅O₇I > Bi₅O₇I > Degussa P25.     

Combination of MoS2 nanopetals with Ag nanoparticles decorated graphene oxide for boosting photocatalytic abatement of recalcitrant pollutants under visible light irradiation

Herein, various weight ratios (1:1, 1:3, and 3:1) of MoS₂/GO composites decorated with Ag nanoparticles (named as MAG) have been prepared by microwave-assisted route. XRD and XPS investigations indicated the catalyst crystallinity and elemental oxidation states. Morphological analysis revealed presence of small MoS₂ nanopetals scattered on GO sheets with Ag NPs dispersed on surface whereas BET-analysis disclosed its excellent surface area (～88 m²/g). Optical properties of MAG catalysts revealed that they were highly visible-light active, with a bandgap of 2.15 eV and a lower charge recombination rate. Excellent efficiency was observed for TC (90.7%; 0.0186 min^?1) and FIP-degradation (85.2%; 0.0177 min^?1) with 4 mg MAG (3:1) catalyst at neutral pH under visible-light irradiation owing to high synergistic interaction (～2.21) in the composite. Effects of catalyst amount, pH, and effective area of illumination on degradation were investigated. High reusable nature of the catalyst (65% (TC) and 58% (FIP) efficiency after 5 cycles) was supported by post-photocatalytic characterization studies. Photodegradation products of TC were determined via LC-MS studies. Holes and hydroxyl radicals were majorly involved in degradation process revealed by trapping studies. High COD (70.4%) and TOC (55.1%) removal rates confirm high photo-mineralization of real-wastewater without any pre-treatment. The current investigation, combined with comparative literature, illustrates real-world potential of MAG catalysts for eradication of resistant pollutants.     

Photocatalytic degradation of phenol under visible light using electrospun Ag/TiO2 as a 2D nano-powder: Optimizing calcination temperature and promoter content

Phenol is one of the toxic materials, and releasing it into the water can be quite irritating and harmful to the health of organisms and the environment. In this study, phenol degradation was investigated using Ag/TiO₂ electrospun nanofiber photocatalyst as a 2D nano-powder. Nanofibers have 2 dimensions in the range of nanometers but their length of them are in the range of micrometers. The micrometer size is an advantage for the separation of the photocatalyst from the suspension. Though, nanometer size is suitable for increasing the available surface for the light. The effect of silver content (0.5–15%) as a promoter and the calcination temperature (300–900 °C) was studied on the degradation of phenol over the synthesized nanofiber-based photocatalyst. Photocatalysts were characterized by various techniques including N₂-physisorption, XRD, SEM, EDX, TEM, FTIR, TGA/DSC, TPO, and DRS. The results have indicated that 5% of Ag content on TiO₂ is the best promoter loading in these experiments. Furthermore, the calcination temperature of 450 °C is found to be the optimum value with an optimum rutile fraction of 23.8%. Maximum phenol degradation was 82.65% at pH = 7, catalyst dosage of 1.5 g/L, and phenol concentration of 5 ppm under a low power visible light (18 W).     

Nanosized BiVO4 with high visible-light-induced photocatalytic activity: Ultrasonic-assisted synthesis and protective effect of surfactant

Nanosized BiVO₄ with high visible-light-induced photocatalytic activity was successfully synthesized via ultrasonic-assisted method with polyethylene glycol (PEG). The BiVO₄ sample prepared under ultrasonic irradiation with 1 g PEG for 30 min was consisted of small nanoparticles with the size of ca. 60 nm. The effects of ultrasonic irradiation and surfactant were investigated. The nanosized BiVO₄ exhibited excellent visible-light-driven photocatalytic efficiency for degrading organic dye, which was increased to nearly 12 times than that of the products prepared by traditional solid-state reaction. Besides decoloring, the reduction of chemical oxygen demand (COD) concentration was also observed in the degradation of organic dye, further demonstrating the photocatalytic performance of BiVO₄. After five recycles, the catalyst did not exhibit any significant loss of photocatalytic activity, confirming the photocatalyst is essentially stable. Close investigation revealed that the crystal size, BET surface area, and appropriate band gap of the as-prepared BiVO₄ could improve the photocatalytic activities.     

膨润土负载红磷复合材料的吸附富集-定位光降解性能

为了提高红磷催化剂的光催化性能, 选择剥离膨润土(EB)为载体, 将水热处理后的红磷(HRP)负载在EB上, 制得EB/HRP复合光催化剂, 并通过不同手段对催化剂进行表征。选择罗丹明B为模型污染物, 考察了EB/HRP复合光催化剂的光降解性能。结果表明, 随着EB含量的增加, EB/HRP复合光催化剂的光降解效率呈现先增加后减小的趋势, 当EB的质量分数为9%时, 复合光催化剂(EB₉/HRP)表现出最强的吸附性能和光降解性能, 其降解速率常数k值为0.0641 min^-1, 是HRP的2倍。另外, 经过五次循环光降解实验, EB₉/HRP仍具有较高的光催化活性(96.8%)。因此, EB₉/HRP复合催化剂具有较好的光催化活性和稳定性, 有望成为一种降解污染物的高效而稳定的光催化剂。     

In3+-doped CuS thin films: physicochemical characteristics and photocatalytic property

Semiconducting Indium-doped copper sulfide thin films were deposited on glass substrate by a simple and economical chemical bath deposition technique. The depositions were carried out for 40 min. The electrical studies namely resistivity, resistance, and sheet resistance of CuS and CuS: In were carried out using four-point probe apparatus. The structural, optical, and morphological characterization were studied and compared with those of CuS: In with the bare CuS thin films. XRD studies confirmed that all the prepared thin films have the hexagonal structure of copper sulfide without any secondary phase after doping and the crystallite size was found to be decrease from 69 to 53 nm. Optical absorption analysis of samples shows a red-shift in the band edge of In: CuS thin films relative to CuS film so that the bandgap energy was decreased from 1.95 eV to 1.86 eV. The functional groups present in the CuS and In: CuS samples were confirmed by FTIR and FT-Raman frequency assignments. Morphological studies of CuS and CuS: In are interpreted using SEM and constituents present in the prepared thin films are viewed by EDS. Further the photocatalytic properties of the prepared films were studied by degrading methylene blue (MB) and rhodamine B (RhB) textile dyes. Maximum degradation efficiency achieved by the photocatalyst is to be 95% and 93% respectively for MB and RhB.

     

Cu-BTC metal organic framework (MOF) derived Cu-doped TiO2 nanoparticles and their use as visible light active photocatalyst for the decomposition of ofloxacin (OFX) antibiotic and antibacterial activity

Herein, we report the ultrasonic-assisted precipitation technique for the fabrication of Cu-doped TiO₂ nanoparticles. The prepared sample showed high crystallinity, purity and nanoparticles like structure with the diameter in the range of 10–22 nm. The bandgap for Cu-doped TiO₂ nanoparticles was estimated to be 2.91 eV using Tauc plot, which is considerable for improving the light-harvesting capacity. Further, the prepared Cu-doped TiO₂ was used as photocatalyst for the eradication of ofloxacin (OFX), an antibiotic from an aqueous phase under visible illuminations. About 72% degradation of OFX (10 mg/L, pH 7) was achieved with Cu-doped TiO₂ nanoparticles after 180 min of visible illumination. The probable photocatalytic mechanism for the decomposition of OFX has been proposed based on reactive species trapping study. Moreover, the antibiotic efficiency of OFX was investigated against Escherichia coli and it was observed that its antimicrobial activity was significantly diminished after the photocatalytic decomposition of the OFX solution with synthesized nanoparticles.     

肖特基型光催化剂研究进展

贵金属与半导体复合形成的催化剂具备肖特基结结构,该结构具有整流特性和较低的界面电压,可以调控光生电子的产生和流向,使电子和空穴更有效地分离,提升光催化性能.综述了近年来肖特基半导体光催化剂的研究进展,分析了晶面沉积、形貌结构、表面等离子体效应及共掺杂等因素对该类催化剂性能的影响,从降解污染物、制氢、二氧化碳还原等方面阐述了这类催化剂在环境控制领域的实际应用,并提出了势垒高度、产物控制及催化剂循环利用等潜在的研究方向.肖特基型光催化剂独特的性质将使其成为新的研究热点,得到更深入的研究和应用.     

肖特基型光催化剂研究进展

贵金属与半导体复合形成的催化剂具备肖特基结结构,该结构具有整流特性和较低的界面电压,可以调控光生电子的产生和流向,使电子和空穴更有效地分离,提升光催化性能。综述了近年来肖特基半导体光催化剂的研究进展,分析了晶面沉积、形貌结构、表面等离子体效应及共掺杂等因素对该类催化剂性能的影响,从降解污染物、制氢、二氧化碳还原等方面阐述了这类催化剂在环境控制领域的实际应用,并提出了势垒高度、产物控制及催化剂循环利用等潜在的研究方向。肖特基型光催化剂独特的性质将使其成为新的研究热点,得到更深入的研究和应用。     

Ag@graphene oxide nanocomposite as an efficient visible-light plasmonic photocatalyst for the degradation of organic pollutants: A facile green synthetic approach

We report a simple and effective supercritical route to decorate silver nanoparticles (Ag NPs) on graphene oxide (GO) using a commonly available and non-toxic glucose as a reducing agent. Transmission electron microscopy and energy-dispersive X-ray analysis confirmed that Ag NPs of size around 8–20 nm were coated on the GO surface under optimized experimental condition. Ag NPs on the GO surface were predominantly spherical in shape and well dispersed. The experimental results proved that the as-synthesized GO/Ag nanocomposite could be used as a highly efficient photocatalyst for the degradation of Rhodamine 123 dye and acetaldehyde under visible-light irradiation. The degradation results indicated that the photocatalytic performance of nanocomposite was greatly enhanced owing to the improved adsorption performance and separation efficiency of photo-generated carriers. The nanocomposite maintains a high level activity even after four times of recycle. Furthermore, the nanocomposite exhibited excellent antibacterial activity against gram-positive and gram-negative microorganisms.     

The pre-acidizing corrosion on the surface of TiO2 enhanced the photocatalytic activity of g-C3N4/TiO2

In this work, g-C₃N₄/TiO₂ nanocatalysts were prepared by high-voltage electrospinning and hydrothermal methods. The surface of the pure TiO₂ nanomaterial was treated by acidification before it was combined with g-C₃N₄.Various characterization methods were used to characterize the prepared photocatalyst. RhB (20 mg/L) was degraded as a target-degradable pollutant, the degradation efficiency of the nanocatalyst was measured under UV–Visible light. The results show that the degradation efficiency of the g-C₃N₄/TiO₂ nanocomposite material that has undergone pre-acidification treatment is much higher than that of the untreated catalyst.

     

基于聚多巴胺的超疏水棉织物的一锅法制备及其油水分离性能

将棉织物浸入多巴胺、硝酸银、十六烷基三甲氧基硅烷的乙醇溶液中,取出烘干制备出超疏水棉织物。用扫描电子显微镜和X射线光电子能谱表征其表面形貌和元素,用接触角测量仪测量其接触角并进行摩擦或液体浸泡(如酸、碱、沸水)实验检测其耐用性。结果表明,聚多巴胺的强附着性使原位生成的银纳米粒子能经受摩擦或不同液体的浸泡,从而使超疏水织物具有良好的耐用性。超疏水棉织物还具有良好的油水分离性能,其油水分离效率高达97%,油流量最高可达15.93 m³·m^-2·h^-1。     

酞菁钴/MCM-41的制备及其可见光催化性能

以MCM-41分子筛为载体,采用浸渍法将酞菁钴负载到分子筛上以氙灯为光源降解甲基橙溶液。对负载型酞菁钴催化剂进行FT-IR、XRD、SEM表征,结果表明所制催化剂负载效果良好,且分子筛结构未发生改变。以甲基橙溶液为模拟处理对象,研究催化剂的催化性能,考察了光照、酞菁钴负载、催化剂用量等因素对催化效果的影响。结果表明,氧气充足时,在光照条件下、0.04g负载型酞菁钴催化剂处理200mL的0.05g/L甲基橙溶液能够有很好的处理效果,2h降解率能够达到98.3%,且重复利用4次后降解率仍能达到90%。     

Carbon supported silver (Ag/C) electrocatalysts for alkaline membrane fuel cells

This study reports on the performance of activated carbon supported silver catalyst (Ag/C) as electrocatalyst in an alkaline membrane fuel cell (AMFC), using alkalized poly (styrene ethylene butylene poly styrene) [APSEBS] as the electrolyte membrane. Carbon supported silver catalyst (Ag/C) with different metal loading was synthesized by means of wet impregnation method. The prepared electrocatalyst was characterized by X-ray diffraction pattern (XRD), thermogravimetric analysis (TGA), UV–Visible diffuse reflectance spectra (DRS-UV) and Raman spectroscopy. Surface morphology analysis of the prepared electrocatalyst using scanning electron microscopy (SEM) revealed the heterogeneous distribution of Ag on carbon support. The performance of the prepared electrocatalyst was evaluated with a home made AMFC using a novel anion exchange membrane (APSEBS). A maximum cell voltage and power density of 0.69 V and 109 mW/cm², respectively, was achieved at 60 °C for the home made 10 wt% (Ag/C) cathode catalyst and anion exchange membrane. Further, the prepared electrocatalyst was subjected to cyclic voltammetry studies to evaluate the methanol oxidation for Direct methanol alkaline fuel cell (DMAFC) applications.